A semiconductor device includes a first semiconductor substrate, a second semiconductor substrate, and at least one guard structure including a first guard element, a second guard element, and a third guard element. The first semiconductor substrate and the second semiconductor substrate are bonded to one another at a bonding interface between a surface of the first semiconductor substrate and a surface of the second semiconductor substrate. The first guard element is in the first semiconductor substrate and spaced apart from the third guard element by a portion of the first semiconductor substrate. The second guard element is in the second semiconductor substrate and spaced apart from the third guard element by a portion of the second semiconductor substrate, and the third guard element includes portions in the first surface and the second surface to bond the first semiconductor substrate to the second semiconductor substrate.